The present invention relates to impact absorbing devices, and in particular to an energy absorbing impact system and related method for vehicle bumpers and the like.
Typical automotive bumper systems include three key components. The first component is a decorative fascia, usually constructed of plastic or the like. The second component is a rigid impact beam, typically constructed of roll formed or stamped steel, which supports the decorative fascia. The third element is an energy absorption unit or assembly that operably connects the impact beam to the frame rails of an associated vehicle. These three components are designed together to meet the performance requirements for both low and high speed impacts.
It is beneficial to design the bumper system in such a way that limited damage is transferred to the vehicle frame rails under impact. One guideline provided for this design process is for the bumper system to have a peak loading capability equivalent to around 85 percent of the combined rail capacity. This assures that the energy absorption unit will crush first upon impact before loading is imparted to the frame rails. It is also beneficial that the bumper system be designed so that energy can be absorbed in a controlled and repeatable manner. This allows for consistency in vehicle crash behavior.
Examples of energy absorption units in bumper systems can be found in U.S. Pat. Nos. 5,427,214; 5,723,801; and 4,272,114, which disclosure various methods of meeting the energy absorption targets for certain vehicle bumper systems. However, such prior devices include certain shortcomings, including inconsistency in deformation and resultant energy absorption, instability in lateral loading, high manufacturing costs, and post impact damage visibility.
While some energy absorption bumper systems incorporate an invertible crush member, the same have a cylindrical shape with scored sidewalls to control inversion and associated energy absorption. These designs sometimes experience problems in achieving consistent tear patterns and repeatable energy absorption characteristics.
One aspect of the present invention is an energy absorption impact system for vehicle bumpers and the like, comprising a base member adapted to be mounted to a vehicle frame, and including a central opening therethrough. An impact receiving member is positioned a spaced apart distance from the base member, and is configured to be operably connected with an associated vehicle bumper. The energy absorption impact system also includes an invertible, tubular energy absorbing crush member having a generally square lateral cross-sectional shape, with generally flat face portions thereof disposed between opposite comer portions thereof. The crush member has a first end thereof connected with the impact receiving member, and a second end thereof with face portions partially slit longitudinally to define generally planar tabs which are flared outwardly and connected with the base member adjacent the central opening, whereby impact on the impact receiving member forces the crush member through the central opening in the base member, causing the face portions to tear longitudinally away from the comer portions as the crush member inverts through the central opening to absorb energy associated with the impact.
Another aspect of the present invention is a method for making an energy absorption impact system for vehicle bumpers and the like, comprising the steps of forming a rigid base member with a central opening extending therethrough, and mounting the base member on an associated vehicle frame. The method also includes forming an impact receiving member, and positioning the same a spaced apart distance from the base member, and mounting the impact receiving member on an associated vehicle bumper. An invertible energy absorbing crush member is formed from a section of tubing having a generally square lateral cross-sectional shape, with generally flat portions thereof disposed between opposite corner portions thereof. One end of the crush member is connected with the impact receiving member, and the opposite end of the crush member is partially slit in a longitudinal direction to define generally planar tabs that are flared outwardly and connected to the base member adjacent the central opening, whereby impact on the impact receiving member forces the crush member through the central opening in the base, causing the face portions to tear longitudinally away from the corner portions as the crush member inverts through the central opening to absorb energy associated with the impact.
The principal objects of the present invention are to provide an energy absorption impact system that is particularly adapted for use with vehicle bumpers and the like. The energy absorption impact system achieves controlled, repeatable and consistent energy absorption performance, yet is economical to manufacture and can be easily installed and/or replaced. An energy absorbing crush member tube has faces that are split along the opposite comers to form spikes which initiate stable tearing conditions and assure the designed energy absorption characteristics. The energy absorption impact system is capable of a long operating life, and is particularly well adapted for the proposed use.
These and other advantages of the invention will further understood and appreciated by those skilled in the art by the reference to the following written specification, claims, and appended drawings.